Module 3 : MAGNETIC FIELD
Lecture 20 : Magnetism in Matter
 
\begin{displaymath}i = A\epsilon_0 \frac{dE}{dt} = \epsilon_0 \frac{d\phi_E}{dt}\end{displaymath}
  where $\phi_E$ is the electric flx through the capacitor.
  Maxwell suggested that a term $\epsilon_0 d\phi_E/dt$ should be considered as current through the dielectric. He termed this current as displacement current. The Ampere's law is modified to read
 
\begin{displaymath}\oint \vec B\cdot d\vec l = \mu_0 \left(i + \epsilon_0\frac{d\phi_E}{dt}\right)\end{displaymath}
  Equation above is now logically consistent because inside the dielectric $i=0$ and the value of the integral is given by the second term. The current exists whenever the electric field, and hence the electric flux, is changing with time. Using Stoke's theorem, we may convert the above to a differential form
 
\begin{displaymath}\vec\nabla\times\vec B = \mu_0\vec J + \mu_0\epsilon_0\frac{dE}{dt}\end{displaymath}
  Exercise-2
  Example-25

Exercise-3
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